Surgeons Pinpoint Kidney Tumors with 3D Printed Color Models

Representing a significant advancement in complex surgical procedure planning, Stratasys color, multi-material 3D printing is being increasingly deployed to aid surgeons who treat a variety of conditions, from heart malformations and hip replacements to brain tumors.

Using Stratasys’ transparent VeroClear material enablesDr. Bernhard to see inside the kidney and estimate the specific location and depth at which the tumor resides

At the Department of Urology and Kidney Transplantation at the University Hospital (CHU) de Bordeaux in France, physicians are using the models during pre-surgery planning. The operations entail complicated kidney tumor removal, and the models help surgeons to perform precise and successful kidney-sparing surgery and to improve patient outcomes. The 3D printed models are also used during surgical training, as well as to enhance communication to patients.

The advanced surgical process, which utilizes combined transparent and color 3D printed models produced on Stratasys’ color, multi-material 3D Printer, the Objet500 Connex3, is being pioneered at the French hospital. According to CHU surgeon Dr. Jean-Christophe Bernhard, CHU is one of the first in the world to deploy Stratasys multi-color, multi-material 3D printing technology for complex kidney tumor removal cases.

“Having a 3D printed model comprising the patient’s kidney tumor, main arteries and vessels – each in a different color – provides an accurate picture of what we will see during operations,” says Dr. Bernhard. “The ability to visualize the specific location of a tumor in relation to these other elements, all in three dimensions, greatly facilitates our task and is not something that is easily achievable from a 2D scan.”

Increasing the opportunity for kidney-sparing surgery

According to Dr. Bernhard, the clearer view offered by the 3D printed model may increase the ability to perform precise and successful kidney-sparing surgery. The pre-surgery planning aids in identifying and avoiding damage to the delicate nearby arteries and vessels which can necessitate complete kidney removal. Sparing the patient’s kidney is important because it reduces the chance of subsequently suffering from chronic kidney disease.

“3D printing technology has effectively heralded a new dawn,” says Dr. Bernhard. “A scan gives us good information, but it’s in 2D. This relies on the surgeon to mentally reconstruct the tumor volume in 3D and estimate its location inside of the total volume of the kidney. The same process has to be done to clearly understand the relations between the tumor, the vessels (arteries and veins) and the collecting system. As you can imagine, this is difficult and time-consuming for the surgeon.

For Dr. Bernhard, the only thing more accurate than a multi-material color 3D printed model of a patient’s kidney is the patient’s kidney itself

“Conversely, having a 3D printed kidney model in your hands that corresponds specifically to that of the patient you’re going to operate on quite literally offers me a view from a new perspective. The only thing more accurate than that is the patient himself.”

“The Stratasys transparent material is of fundamental importance as it allows us to see inside and estimate the depth at which the tumor resides,” says Dr. Bernhard. “It enables us to see the arteries and the cavities that collect urine, so we can see if any of the arteries are touching the tumor. We need to remove the tumor, but not at the expense of the other vital elements that together enable the kidney to do its job. Finding that balance is much easier to achieve thanks to 3D printing.”

Dr. Bernhard also believes that use of 3D printed models will not be restricted to kidney surgery, and he sees them being equally useful for any organ-sparing surgeries.

Training the surgeons of tomorrow

Stratasys 3D printing solutions also significantly strengthens the CHU’s capabilities from an instructional standpoint. For Dr. Bernhard, this is a fundamental benefit of 3D printing and one that he sees making a big impact within the medical sector long-term.

“I think this technology will be a big driver in terms of shaping the future of teaching and surgical training,” he says. “Having access to a 3D printed model that is completely accurate to the one on which you’re going to operate not only enables you to train yourself on the operation, but it also greatly improves our ability to more accurately convey surgical procedures to students – who, of course, are the surgeons of tomorrow.”

Reassurance by improved patient understanding

Another major benefit for the CHU of Bordeaux and Dr. Bernhard is the ability to use the 3D printed models to more easily explain procedures to patients prior to surgery, thereby offering increased reassurance.

“Describing kidney tumor removal with 2D scan or a diagram will invariably leave most patients somewhat bewildered,” he explains. “Presenting them with a 3D printed model that clearly shows the tumor puts them at ease and enables the patient to grasp exactly what we’re going to do. Indeed, research from patient questionnaires shows that having 3D printed models increases their understanding of the surgery by more than 50%, so it’s a considerable benefit in terms of overall patient care.” (1)

Commenting on the use of 3D printing technology at the hospital, Scott Rader, General Manager of Medical Solutions at Stratasys, says, “By putting exactly what the surgeon needs to see right in his hands, the pioneering use of Stratasys color multi-material 3D printing technology at the CHU de Bordeaux demonstrates its capability to improve medical operations by decreasing complexities to make the surgeon’s role easier. Moreover, by enhancing procedures in this way, the prospect of organ–conserving surgery is increased, resulting in a far more favorable outcome for patients.”

There are a number of methods for converting patient imaging into 3D printable files. In general, the options are to (a) use autosegmentation provided by the vendor of imaging systems such as Vital Images Vitrea Software (b) use open source/freeware software such as Invasalius or 3DSlicer or (c) use professional software such as Materialise Mimics. Depending on the complexity and quality of the imaging, segmentation can take less than an hour or a full week. Here is a white paper we have created summarizing the process and options: http://usglobalimages.stratasys.com/Main/Secure/Technical_Application_Guides-TAG/TAG_DU_MedicalSegmentation_1016a.pdf